What To Do When Considering The Placement Of A Metal Roof Over Asphalt Shingles
If you want to install a metal roof on your home and the asphalt one currently in place is in fair to good condition, then you may be able to simply install the metal over the shingles. This is a great choice if you want to save yourself on time and costs. There are a few things you should do beforehand though. So, keep reading to learn what they are.
Consider The Shingle Depth
While the vast majority of homes will have a double layer of asphalt shingles, some will actually have three distinct layers. This happens when the old roof is not torn off and another layer is simply added over the top of the shingles. In this case, all three shingle layers will need to be removed before the steel is added. In this scenario, the additional metal will add too much weight to the roof and you may be at risk of a roof failure and collapse.
In some areas, codes will stipulate that you can only have two layers of roofing material on a roof. So, if you already have two layers of shingles, then you cannot add a third with the steel.
Since you may not actually know how many layers of shingles you have on your roof, pull up the shingles on the edge of the roof and count them. Then, speak with your local zoning board or municipality to see what the building codes are in relation to roofing.
Keep in mind that if you have too many shingles to add the metal roof on top, you will need to tear off the entire roof instead of simply remove one or two layers of shingles. This has to do with the way the shingles are adhered to the sub base.
Look At Ventilation
Steel roofs are not simply placed on top of the shingles. They are actually adhered to a series of two by fours that are formed into a grid on the roof. So, there is a bit of space between the asphalt shingles and the steel sections. Water can accumulate in this region, so you need to be mindful of ventilation and how water can escape from the roof if it seeps under the metal.
For ventilation purposes, holes can be formed in the shingle roof close to the soffits. The size of the holes should correspond to the amount of moisture that may accumulate, so they may be bigger in areas that see a great deal of snow and rainfall.
Also, ridge vents must be added. This can be confusing if you are not experienced with home improvement projects, so speak with a roofing specialist if there is a concern. Companies like Welty Custom Exteriors, Inc can help.